November 14, 2012

Climate Model Shows That Warming Could Change The Face Of Greenland

There are almost as many global climate models as there are climate scientists. Even with all of these models, however, it's very difficult to pin down how warming temperatures globally will affect any specific region.

A research team from The City College of New York and the University of Liege, Belgium, and supported by the National Science Foundation (NSF), have made the "global local" using the output of three global models and one regional climate model. With this configuration, the team can predict how different greenhouse gas scenarios would change the face of Greenland over the next century, and how this would affect sea level rise.

The result is a high-resolution picture of the island's future via a fine-scale model.

“We put Greenland under a microscope to see what accounts for melting and for ice mass changes in different regions,” said Dr. Marco Tedesco, associate professor of earth and atmospheric sciences at The City College of New York. The findings of this study were published online in the journal Environmental Research Letters.

Tedesco and his colleague, Xavier Fettweis of the University of Liege, compared two possible future CO2 scenarios. First, a concentration of carbon dioxide in the atmosphere projected for the end of the century of 850 parts per million (ppm), which approximates the current rate of increase. The second scenario was a more aggressive 1370 ppm.

In both scenarios, the Greenland ice sheet would lose more ice and snow to melting than it would accumulate, with the greatest losses in basins on the southwest and north coasts. There would only have to be a temperature increase of 0.6 to 2.16 degrees Celsius to tip the balance into more loss than gain.

Melting would alter the topography of Greenland, potentially affecting adjacent ocean circulation and salinity, according to the new model. This could speed further melting.

Tedesco warns that although the predictions seem dramatic, they might be too conservative.

“They don´t take into account progressive effects of the changing elevations and topography and the acceleration of ice sheet movement.”

However, these results represent an important step forward toward understanding the potential repercussions of warming temperatures. Tedesco says this is an improvement on models that give a coarser view of the future.

“Some areas will be 400 meters below the current elevation just because of melting. This might very well impact the speed and amount of ice that is flowing to the ocean. It would increase the rate of melting, because conditions get warmer at lower elevations” he noted. “Imagine an ice cream that is melting much faster in one area. This will change the shape of the ice mass over Greenland.”